# Questions tagged [circuit-analysis]

Circuit (Network) analysis is the process of finding the voltages across, and the currents through, every component in the network.

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### What textbook is this problem from? (circuit analysis)

A somewhat unusual question: Some years ago, the following problem appeared in a test I took during my Bachelor's in electrical engineering. Later, the professor told us which textbook he took it from,...
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### Can this Raspberry Pi UPS circuit work?

I created following UPS circuit to shutdown my Raspberry Pi 3A+ properly: I would really appreciate if somebody can review my circuit. I know it's a little bit hard to read, but I'm sorry. I'm a ...
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### Why is the imaginary part absent in the BJT gain calculation?

The gain of transistor Q1 was previously calculated in this post simulate this circuit – Schematic created using CircuitLab It was found to have a gain of about 2.92. Now I change the ...
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### automatic submersible pump actuation project

I have a project for automatic submersible pump actuation using a microcontroller. I've done for two voltages like 5 V and 12 V and its corresponding relay. Also, in each board there is a transistor ...
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### Power stage for VCR (Voltage Controlled Resistor)

I'm building a VCR (Voltage Controlled Resistor) using the LM13700 component. You can read more details on that here: Floating voltage-controlled resistor with LM13700: How does it work? The problem ...
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### Why is each time constant in this transfer function equal to "open circuit" time constant not "short circuit" time constant?

From this lecture notes, the open circuit time constant approximation: How to prove the yellow part? The lecture note mentioned Richard Adler at MIT did prove this but I could not able to find his ...
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### Capacitor current in parallel network with ESR and parallel resistance

So this might be a very simple question and I've got a knot in my brain but I've been at this for days and don't see how I could solve this problem. I'm trying to find the solution for both ucA, ucB(t)...
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### How to compare Matlab/Theory <=> Cadence: Switched-cap. Integrator: Mag & Phase

I tried to compare the simple switched-capacitor integrator below, between Cadence and Matlab (at the end acting as a simple loop-filter for a delta-sigma). I am stuck now on the point of how to ...
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### Need help with an IR demodulation circuit

I'm trying to reverse engineer a PCB and made a schematic. The bad thing is I only have PCB images from both sides, not the actual PCB. This PCB is used to detect a very small black object spinning at ...
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### Where does the 1V voltage come from?

I have a four PLC with many digital I/O connected similarly to the schematic below. If I use multi meter and measure the voltage between the two points in the schematic, why is it showing 1V? Isn't it ...
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### How do determine MOSFET parameters in LTSPICE

I am designing a phase locked loop on LTspice (which I'm new to), but have come across a snag in the procedure: Is there a way to determine the output resistance of a mosfet (as the I'm not able to ...
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### Intuition on Thevenin's Theorem

In the following lecture by Prof. Anant Agarwal at 36:00, he intuitively proves Thevenin's Theorem using the following circuit simulate this circuit – Schematic created using CircuitLab If ...
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### How do I calculate limit frequency of the attenuator circuit?

Calculate the limit frequency $fg$ of the attenuation $v_u =\frac{ u_a} { u_e}$ at the current source I (for the value given in example), so that for $f>> fg$ exist ideal behavior. Note: ...
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### Is state variable analysis used much in circuit analysis these days?

I am an older EE and I have used the old tried and true methods of circuit analysis like KVL, KCL and some Signal Flow Graph methods. Recently I have been reading about methods that were originally ...
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### Appoximation of a transient response of a more complex circuit

I have a "complicated" circuit that I want to approximate as a simple harmonic oscillator. More info below. I have a parallel LRC circuit, with some extra input and output load resistors and coupling ...
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### About MOSFET circuit behavior

When I look at the waveforms of simulated circuits, how do I know when their behavior (for example flipping value stored on a node, or an unexpected drop in strong level value...) is due to MOSFET ...
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### Sensitivity of Inrush Current Circuit

I'm new to LTSpice and analog design - I'm having a bit of a struggle getting a feel for the behavior of this inrush limiting circuit. Stole the design from another SE post, but playing with the ...
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### RHP pole of two stage OTA

I learnt that for any amplifier (with some capacitor) if we short/open the capacitor and the polarity of gain changes, it is a sign of RHP zero. Now, while applying the same analysis I obsevred that ...
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### Current Direction and Voltage Polarity in Capacitor/Inductor Circuits

I believe that this question may be simple for those with a little more experience, but it is still puzzling me. Studying capacitance/inductance, I understand that the capacitor in the DC case behaves ...
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### Can anyone help me figure out what this circuit does?

I wanted to see if anyone might be able to help me understand this circuit board a bit better. I am trying to trace some issues I'm having with my car stereo and this board is the furthest I can trace ...
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### Small signal analysis of MOSFET circuit

The other day I got the following exercise on one of my exams: For those who don't speak German, for transistor 1 lambda is 0, but not for the others. The backgate-effekt should be neglected ...
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### Finding the mathematical function that describes voltage across diode and resistor circuit

I have the following circuit: simulate this circuit – Schematic created using CircuitLab Where $\text{V}_\text{i}\left(t\right)=\hat{\text{u}}\sin\left(\omega t+\varphi\right)$ and the ...
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### Ideal Transformer Currents Relationship

I'm currently quite confused with the relationship of the currents for an ideal transformer when it overlaps with multiple mesh currents. It was defined that for: \frac{\bf I_2}{\bf I_1}=\frac{1}{n}...
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### How should fuse selection be made in discrete-time alternating current?

My V(t) signal progresses for hours as 0.75 seconds on,5 seconds off.(Let assume V(t)=I_lamp(t),R_lamp=1 ohm) The general formula for fuse selection at room temperature is: In summary,what should I ...
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### 555 PWM circuit set frequency shifting after 2 months

Please refer to post PWM generator circuit review for initial simulation and bugs on the circuit. In general, the circuit works very well and I can control a 12V fan with the PWM output of the 555 ...
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### finding state space equation in x=Ax+Bu form

Can anyone please help me to find the state space equation of this circuit diagram in the form of x=Ax+Bu? The equation I am getting is not giving me square matrix. Can anyone help please? These are ...
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### karnaugh table issues

Hello,I have this truth table.I did this table and I am creating a demultiplexer 1 in 2.Not multiplexer. Second,I did and that I gave and those Am I right?I want to confirm that I have done it all ...
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### Left half and right half plane zeros

In the common-source on the left, one can solve for the transfer function and see that there's a right-half plane zero at $s_z = +g_m/C_{gd}$. For the source-follower on the right, similarly you can ...
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### Thermal Noise in Oscillators

let's consider this circuital model for an LC oscillator in which the parasitic resistance R is affected by thermal noise (represented here with an equivalent noise current source, according to the ...
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### Op-Amps in custom current limiter acting strangely

I'm building a small current limiter (~20 mA). It's important that there is little drop over the current limiter and that the load receives almost the full supply voltage when it's pulling less than ...
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### Circuit Analysis: Difficulty in obtaining a current through a resistor?

I'm solving a problem that requires I compute some impedances, and then the current through a resistor. I obtained some of the impedances*, but don't know how to get the second part (current). ...
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